1. Field of the Invention
The present invention relates to a solar cell module-mounting structure, a solar cell module array and a photovoltaic power generation system.
2. Related Background Art
The raised awareness of environmental issues has been spreading globally. Particularly, the concern about global warming phenomenon associated with CO2 emission is serious, and the desire for clean energy has been increasing. At present, a solar cell module can be expected as a clean energy source for safety and easy handling.
Recently, various types of forms for mounting the solar cell module other than a roof-mounting type have been proposed as described below.
FIGS. 2A and 2B are schematic views of the solar cell module structure using a conventional rack-mounted-type solar cell module. In FIGS. 2A and 2B, numeral 2001 denotes a solar cell module; 2002 denotes a concrete foundation; 2003 denotes a frame; and 2004 denotes an anchor.
The structure of this type solar cell module is characterized by a structure in which the solar cell module is incorporated into a frame such as an aluminum frame to maintain structural strengths, the front surface of a photovoltaic element is sealed by glass and the bottom surface thereof filled and sealed by plastics to secure sufficient electric insulation properties and weathering resistance, and anchors are hammered into the ground to increase wind pressure resistance strength of the rack itself. The solar cell module of this type has come into widespread use as the most typical one at present.
On the other hand, as a base material for the rack and the solar cell module, a concrete member has been paying attention recently because of its low price.
An example shown in FIG. 3 is known as the one in which a concrete member is used as the rack instead of a conventional frame rack.
FIG. 3 illustrates an example of the rack comprised of a lightweight cellular concrete tailored for a solar cell module described in Japanese Utility Model Laid-Open No. 5-57857. In FIG. 3, numeral 3001 denotes a solar cell module; 3002 denotes a lightweight cellular concrete rack; and 3003 denotes a fastener. According to the construction, a fitting device may be fixed with a nail or the like on the concrete rack, and the rack itself forms an inclined surface for mounting the solar cell module only by placing the rack on the ground, thereby improving workability.
However, not only the conventional rack-mounted solar cell module structure but also the conventional solar cell module-mounting structure using a concrete member as the rack has been limited in cost reduction, because the concrete body has to be prepared as a solar cell module rack having a desired size and an inclination angle.
In view of the above situation, the present inventors have studied the reduction of the material and construction costs of the rack of a solar cell module-mounting structure, and have devised the following structure.
More specifically, a rectangular plate-shaped member is used as a plate-shaped member for supporting the solar cell module, and a support member is used as means for inclining the plate-shaped member for mounting the solar cell module, thus providing the inclination required for mounting the solar cell module to aim to reduce the cost of the materials of the rack and the cost for construction work.
However, in the case of forming the above-described solar cell module-mounting structure, the following problems have become clear.
(Problem of Movement of a Plate-Shaped Member by Wind Pressure)
When a plate-shaped member 403 is installed as shown in FIG. 4, the wind hitting the plate-shaped member 403 in the direction of an arrow 401 generates a force acting in the direction perpendicular to the surface hit by the wind. In other words, a force (lift) lifting the plate-shaped member 403 acts on the fixing-surface 409 of the solar cell module 402 and its opposite surface 405, and a force (drag) moving the plate-shaped member 403 laterally acts on the side surface 404. Generally, these forces are calculated as the product of a wind force coefficient (depending on surface properties and an inclination angle), a wind-receiving area and velocity pressure (proportional to-the square of wind velocity), and the lift and the drag acting on each plate-shaped member increase in proportion to the square of the wind velocity.
Further, when the plate-shaped member 403 is in contact with an installation surface 407 and a support member 406 at one side respectively to be supported as shown in FIG. 4, the area of contact between the installation surface 407 and the plate-shaped member 403 and the area of contact between the support member 406 and the plate-shaped member 403 are small, thereby resulting in a small frictional force between the plate-shaped member 403 and the installation surface 407. When a force as illustrated in FIG. 4 acts in such a state, the frictional force between the plate-shaped member and the installation surface is further decreased due to the decrease of its own weight by the lift, thereby causing the plate-shaped member to be moved laterally even by a wind having a strength smaller than the wind pressure resistance strength of the plate-shaped member.